Improvement of settling performance by initial value compensation considering rolling friction characteristic

This paper presents a novel initial value compensation (IVC) methodology considering rolling friction properties for the fast and precise positioning. Rolling friction in mechanism behaves as a nonlinear elastic element in the micro displacement region, and deteriorates the positioning performance with the slow settling response. In order to improve the performance, a rolling friction model-based feedforward friction compensation is one of promising approaches. However, in the case that the friction model error exists, the model-based compensation approach can not achieve the desired position response during the transient response, resulting in the deterioration of the settling performance with the response variation and the slow response. In this paper, therefore, an IVC using the specified step settling control framework is applied to achieve the required settling performance without the deterioration. Since the proposed IVC can compensate for the effects of the feedforward friction compensation errors during the transient, the overshoot response, which causes the slow settling response, can be suppressed at the settling. The proposed IVC has been verified by experiments using a prototype of linear motor-driven industrial positioning devices.